Hybrid propellant systems use a combination of solid and liquid or gaseous fuels to propel rockets. The solid fuel provides stability and ease of storage, while the liquid or gaseous oxidizer allows for better control of thrust and burn rate. This combination can enhance performance and safety compared to traditional solid or liquid propellant systems. These systems are often used in space exploration and satellite launches, as they can be more efficient and flexible. Notable examples include the SpaceShipTwo and various military applications. Hybrid systems aim to balance the advantages of both propellant types, making them an attractive option for modern rocketry.